Traffic protection apparatus



NOV. 16, 1948. J, H, BROADBENTV 2,454,249

` l TRAFFIC PROTECTION APARATUS' y Filed Apri; V25, 194e 4 C4 za aim Patented Nov. 16, 1948 UNITED STATES PATENT OFFICE Y 12,454,249 'TRAFFICPROTECTION APPARATUS John H. Broadbent, Willistown Township, vChester County, Pa., assignor to The Union `Switch vand Signal Company, Swissvale, Pa., a corpora-` tion ofPennsylvania Application April 25, 1946, Serial No. (664,717

'stop if the 'car or locomotive is within 'fouling `distance of that main track. In crossover protection schemes embodying track circuits, one characteristic should therefore be high shunting sensitivityin order to insure that `the crossover track circuits will rbe shunted if the crossover ytrack has high contact resistance due to infre-f quent train -rnovernentsover the crossover.

One feature of` Vmy invention is the provision of low frequency alternating current track circuits in which the voltage may be arranged to be sufficiently high to provide good `shunting sensitivity. These track circuits farealso so arranged as to provide protection against defective insulated rail joints. i

A further feature of .my invention Vistlle pro- `.vision of `means controlled by a coding devicefor supplying low .frequency `alternating current to `the rails .of one of two sections fof 'a crossover track, and Yof .means also controlledby the `codjin'g device' for frectifyin'g" alternating current en- 'ergy received from the other `track section for :controllingtraic Ygoverning means.

:I shall describe Ione formof apparatus embody- 'ing Ymy invention, and shall thenpoint out the novel ffeaturesthereof Vin claims. i

The :accompanying drawing is a diagrammatic view showing one formof apparatus embodying :my invention.,y i

ASimilar reference characters refer to similar partsinthei'drawing f .Referring tothe drawing, a stretch of railway is shown comprising two ,parallel tracks, designated by the reference ichar'acters IT and '2T,

4 'connected with each `other by a crossover track designated by the ref erence character 3T,y through hand-operated switchesI IW and 2W. Track 3T risdivided, Eby means of `insulated joints-4, intotwo A :coding deviceA ldesignated by the reference character CT :is constantly energized bya suitableV sourcefof current, lnot shown,A but having 2 i terminals designated B and N. Device `C"I`'n1;y have van operating frequency "of 180 cycles. per minute, for example, at which it moves each 1of `its contacts 5 and t between a rstpositionfand a second position in which, as here shown,;itcon nects with front and back points, respectively.

Contact 5 of coding device CT, 'while being operated vbetween its `front and back .pointsfcontrols repeated energization 'of primary winding m of a transformer, designated by the :reference character IF, `alternately in opposite directions. lSecondary winding d of transformer 'liEYfis connested across rails 3a 'and 3b Iof section l1-c, tto which it `supplies low frequency alternating current.

`A second transformer 2F has 'a primary iwinding m connected across the rails of section Ib"c,

A'and a secondary winding d connected acrossthe rails of section af-b. This transformer therefore'transrnits alternating current energy from section b--c to section 'a-b, but at the Sametime prevents the flowoi direct currentb'etwe'en these sections.

A `decoding transformer 3F has vra primary winding 'm which is energized by current received from section c-b. The current output from secondary winding d of transformer 43F is rectified by contact 8 of coding device CT while this .contact is `being operated between its front andb'ack points.

A slow pick-up slow release code detecting relay RP is energized by this rectified current. Contacts il and l2 of relay RP, as here shown, 'con- -tro1 traiiic governing means for tracks `["Iand 2T.

As shown in the drawing, all parts of therapparatus are in :the normal condition, that is, switches VIW and 2W are in the normal position; coding device CT is constantly energized, `and hence its contacts 5 and 'B are being repeatedly closed alternately at their front and back points at a given suitable frequency such for `example .as T80 cycles per minute; primary winding in of transformer IF is repeatedly energized alter- `mately in 'opposite 'directions in response 'to the operation of contact` 5; secondary winding "d of transformer iF is therefore supplying low frequency alternating current to the rails vof section b-c, and hence transformers `2li and '3F in turn are energized, The current output from `secondary winding d of transformer 3F is being rectied by contact At of coding VdeviceCT; and relay RP is therefore energized andits contacts all and l2 are closed in signal control circuits'for tracks yEach timeco'ntactf of coding device CICcl'os'es at its front point, a circuit is closed, passing from terminal B, through the front point of contact 5 of coding device CT, and portion 6 of primary winding m of transformer IF to terminal N. Each time contact '5 closes at its back point, a similar circuit is closed which energizes portion l of primary winding 1n of transformer IF in the opposite direction.

Low frequency alternating current is therefore generated in secondary winding d of transformer IF. This current is supplied, by winding d, to the rails of section b-c, and energizes primary winding m of transformer 2F. Low frequency alternating current is therefore also generated in secondary winding d of transformer 2F. This current is supplied by transformer 2F to the rails of section a-b, and energizes primary winding m of decoding transformer 3F.

Contact 8 of coding device CT closes at its front and back points at the same times that contact 5 closes at its front and back points, respectively. Contact 8, connected as shown, therefore recti- Iies the current output from secondary winding d of transformer 3F. Relay RP is energized by this rectified current, and hence its contacts II and I2 are closed in signal control circuits for tracks IT and 2T, respectively.

When a train occupies crossover track 3T anywhere within fouling distance of track IT or 2T, the track circuit for one or the other of the sections a-b and b-c will be shunted, and hence transformer 3F Will be deenergized. Relay RP will therefore also be deenergized, and hence its contacts II and I2 'will be opened, causing the signals for both tracks IT and 2T to indicate stop. Some of the advantages provided by apparatus embodying my invention are as follows:

ll. Foulz'ng protection-A train occupying crossover 3T at any point within fouling distance of tracks IT and 2T will cause the signals for tracks IT and 2T to indicate stop.

2. Superior shuntz'ng sensitivity- Transformers IF and 2F can be arranged to supply high enough voltages to the rails of sections b-c and a-b, respectively, to break through high contact resistance which might occur due to infrequent use of the crossover track.

3. Broken rail protection-All portions of the track rails included in the track circuits for crossover track 3T are in series, and hence the joints- If th'e insulated joint at a in rail 3a should break down, a track circuit, not shown, for track IT would be deenergized. If the insulated joint at a in rail 3b should break down, transformer 3F would be shunted. If the insulated joint in rail 3a at point b should break down, and if there should be a current leak from rail 2a of track 2T to rail Ia of track IT, tending to connect winding d of transformer IF across the rails of track I T, the successive reversals of polarity of the current from the secondary winding of transformer IF would prevent operation of a track relay for track IT by current from transformer IF. If the coding device CT should fail, and its contacts should stick in either position, primary winding 1n of transformer IF would be constantly energized in one direction, and hence its secondary winding d would be deenergized.

Although I have herein shown and described only one form of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railway track divided into two sections, a coding device having two contacts repeatedly closed at the same time alternately in a first position and a second position while said coding device is energized, a transformer, a secondary winding of said transformer connected across the rails of one of said sections adjacent one end of said stretch of track, means controlled by one of said contacts in its lirst and second positions for repeatedly energizing the primary winding of said transformer alternately in opposite directions, a second transformer the primary winding of which is connected across the opposite end of said one track section and the secondary winding of which is connected across the adjacent end of the other track section, a decoding transformer the primary winding of which is connected across the opposite end of said other track section, a code detecting relay, means including the other one of said contacts for rectifying the current from the secondary winding of said decoding transformer for energizing said code detecting relay, and traflic governing means controlled by said code detecting relay.

2. In combination, a stretch of railway track divided into two sections, a coding device having two contacts repeatedly closed at the same time alternately in a first position and a second position while said coding device is energized, means controlled by one of said contacts while being operated to its first and second positions for supplying low frequency alternating current across the rails of one of said sections, means for transmitting alternating current energy and at the same time obstructing the flow of direct current from said one section to the other section,'

a decoding transformer the primary Winding of which is connected across the rails of said other section, means including the other one of said contacts for rectifying the current output from the secondary Winding of said decoding transformer, and traflc governing means controlled by said rectified current.

3. In combination, a stretch of railway track divided into two sections, a cooling device having two contacts repeatedly closed at the same time alternately in a rst position and a second position while said coding device is energized, means controlled by one of said contacts while being operated to its first and second positions for repeatedly supplying current. of alternately normal and reverse polarity to the rails of one of said sections, a transformer the primary winding of which is connected across the rails of said one section and the secondary winding of which is connected across the rails of the other section, a decoding transformer the primary winding of which is energized by alternating current energy from the rails of said other section, means including the other one of said contacts for rectifying the current output from the secondary winding of said decoding transformer, and traffic governing means controlled by said rectified current.

4. In combination, a stretch of railway track divided into two sections, a coding device, means controlled by said coding device for supplying low frequency alternating current to the rails of one of said sections, means for transmitting alternating current energy and at the same time obstructing the flow of direct current from said one section to the other section, a decoding transformer the primary winding of which is energized from the rails of said other section, means controlled by said coding device for rectifying the current output from the secondary winding of said decoding transformer, and traic governing means controlled by said rectified current.

5. In combination, a stretch of railway track divided intc two sections, a coding device, a transformer the secondary winding of which is connected across the rails of one of said sections, means controlled by said coding device for repeatedly energizing the primary winding of said transformer alternately in opposite directions, means for transmitting alternating current energy but at the same time obstructing the ow of direct current from said one section to the other section, a decoding 'transformer the primary winding of which is energized from the rails of said other section, means controlled by said coding device for rectifying the current outputfrom the secondary Winding of said decoding transformer, and traffic governing means controlled by said rectified current.

6. In combination, a pair of conductors divided into two sections, a coding device, means controlled by said coding device for repeatedly supplying current of alternately normal and reverse polarity to the conductors of one of said sections, means for transmitting alternating current energy but at the same time obstructing the How of direct current from said one section to the other section, means controlled by said coding device for rectifying alternating current energy received from the conductors of said other 6 section, and electrical control means controlled by said rectified energy.

'7. In combination, a section of railway track, a coding device, means controlled by said coding device for repeatedly supplying current of alternately normal and reverse polarity to the rails of said section, a decoding transformer the primary winding of which is energized from said section, means controlled by said coding device for rectifying the current output from the secondary winding of said decoding transformer, and traffic governing means controlled by said rectied current.

8. In combination, a section of railway track, a coding device, means controlled by said coding device for repeatedly supplying current of alternately normal and reverse polarity to the rails of said section, a decoding transformer,` means controlled by current received from said section for energizing the primary winding of said decoding transformer, means controlled by said coding device for rectifying the current output from #the secondary Winding of said decoding transformer, and traflic governing means controlled by said rectified current.

JOHN H. BROADBENT.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 35 1,815,960 Young July 28, 1931 2,123,753 Staples July 12, 1938 2,371,263 Preston 1 Mar. 13, 1945 yCertificate of Correction Patent No. 2,454,249. November 16, 1948.

JOHN H. BROADBENT It is hereby certified that error appears inthe printed specification of the above numbered patent requiring correction as follows:

Column 4, line 51, claim 3, for cooling read coding;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 1st day of March, A. D. 1949.

THOMAS F. MURPHY,

Assistant Oommzssioner of Patents. 

